HOW TO PREVENT CANCERS

As national trends have shown us all too clearly, keeping weight in check can be a difficult journey for many of us, and a lonely one at that. Success or failure when it comes to our weight is often pinned to us as individuals. Yet, individual actions are just the culmination of a broader web of influences in our lives. So, while it certainly comes down to my choice to have a carrot rather than a cookie or go play basketball rather than watch basketball on TV, other influences in my environment can help me make the healthier choice of the two. If my friends are big produce eaters, for example, I’ll be more likely to choose carrots. If my neighborhood has safe parks with basketball courts, I’ll be more likely to choose to play sports rather than watch them.

To have a real and broad influence on weight loss it’s important to make positive changes to the many factors that influence how much we exercise and how much (and what) we eat. In scientific terms, this is called the “ecological model of health behavior.” And while it’s not that important for most of us to know what it’s actually called, it helps researchers look at all the different areas in our lives that influence how we act.

Researchers, Sallis and Owens (Sallis & Owen, 1999), have detailed the key factors that help influence our health choices:

• Intrapersonal factors: These are basically the things within ourselves that influence our choices – our self-motivation, our learned behaviors, our physical abilities, for example.

• Social environment factors: These are the social and cultural factors that promote or discourage a healthy behaviors. These include things like how our friends accept or reject certain behaviors; the healthy (or unhealthy) choices our friends make, and how our broader culture helps promote or discourage certain behaviors.

• Physical environment factors: These include things within the natural environment (such as weather or geography) or the constructed environment (such as bike paths, sidewalks, or safe neighborhoods) that promote or discourage a healthy behavior.

All of these different factors push and pull and sway us to make certain choices. When they’re all aligned it’s much easier to make (and keep up) healthy choices in our lives (see figure). 


When it comes to weight loss and physical activity, research has shown that certain approaches that target one or more of these factors can have positive benefits. Here’s a sampling of findings.

Health care setting
One demonstrated successful approach to improving weight control and increasing physical activity is intensive counseling in a health care setting. These programs not only provide support for making healthy changes but also build solid skills on how to make such changes and keep them up over time. The Diabetes Prevention Trial showed that health care provider-based counseling could reduce weight and increase physical activity over a 24 month period and thereby prevent diabetes (Diabetes Prevention Program Research Group, 2002). A National Cancer Institute intervention based on physician counseling of patients with the “Five A’s” —assess, advise, agree, assist, arrange — has also been shown to be effective.

Interactive technology
Interactive websites and other technologies can also offer many of the same aspects of evidence-based behavior change counseling, including assessing current health behaviors, identifying barriers to change, developing supportive social networks, allowing the patient to set goals and select relevant activities, and arranging follow-up support. And there’s evidence that these technologies can successfully help support lifestyle behavior change (Glasgow et al, 2004).

These tools can also be used at homes, in community centers, in doctors’ offices, or practically anywhere on mobile devices, something that will increase their appeal even more to both busy patients and busy physicians. Studies will show which approaches are successful and which are not.

Physical environment and policy
Changes to public policy and the physical environment have a vast potential to influence large segments of the population simultaneously and, therefore, can often be less costly (on a per capita basis) and more enduring than approaches that focus on convincing individuals to be more active. Rather than simply persuading individuals to change, environmental and policy approaches aim to make it easier for individuals to choose and maintain activities that promote healthy weight. They do this by changing social norms (for example, making it more acceptable to commute to work by bicycle or foot or to exercise during lunch hour) or by changing the environment (for example, improving road and sidewalk conditions for pedestrians and cyclists or making workplace stairways as safe, well-lit, and accessible as elevators).

Given the inherent difficulties of evaluating such population-based approaches to behavior change, there are little published data on the effectiveness of environment and policy approaches to increasing physical activity. In a 1998 review of the topic, Sallis et al. found only seven published studies, with interventions ranging in complexity from the posting of simple signs encouraging the use of stairs to the opening of 14 publicly-funded recreation centers in Belfast (Sallis et al, 1998). Methodological flaws in these studies eventually precluded the authors from reaching firm conclusions about their efficacy.

Yet, lessons from smoking prevention show that policy choices can have major effects on healthy outcomes (Cummings et al, 2009). Each 10 percent increase in the tobacco excise tax finds about a 4 percent drop in smoking rates. And in New York City, broad smoke-free laws show significant drops in heart attack rates across the city in just a single year. Of course, weight loss isn’t tobacco, and nothing can stand in for solid evidence of the weight control benefits for policy and environmental changes, pointing to the need for rigorous evaluation of any such programs put into place.

Summary
Because the factors that influence weight control, diet, and exercise range from the individual to the environment, efforts to shift the whole population toward healthier weight, calorie, and activity levels will require emphasis on all of the intervention points mentioned above: health care settings, social networks, and environment. The challenge for prevention is to develop a comprehensive approach to physical activity and weight control that targets all of these aspects simultaneously.


Literature cited
Cummings KM, Fong GT, Borland R (2009). Environmental influences on tobacco use: evidence from societal and community influences on tobacco use and dependence. Annu Rev Clin Psychol 5:433-58.

Diabetes Prevention Program Research Group (2002) Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin. N Engl J Med 346: 393-403

Glasgow RE, Bull SS, Piette JD, Steiner JF (2004) Interactive behavior change technology. A partial solution to the competing demands of primary care. Am J Prev Med 27: 80-7

Sallis J, Owen N (1999) Physical activity and behavioral medicine. Vol. 3edn. Thousand Oaks, CA: SAGE Publications Ltd

Sallis JF, Bauman A, Pratt M (1998) Environmental and policy interventions to promote physical activity. Am J Prev Med 15: 379-97